The invention relates to a binocular telescope comprising two barrel tubes, each fastened to a bridge and accommodating an objective lens, a focusing lens, a prism system for image inversion, and an eyepiece, wherein the prism system is oriented so that the optical axis of the eyepieces is offset relative to the optical axis of the objective lenses.
In binocular telescopes with objective lenses of relatively large diameter, the optical axes of the barrel tubes on the objective side have a separation from one another which differs greatly from the normal separation of the eyes of an observer. It is therefore known to provide the separation of the optical axes on the eyepiece side with an offset by means of an intermediate prism system.
Adaptation to the individual eye separation is achieved with the aforementioned telescopes in that, for example, the two barrel tubes are rotatably connected to one another via an articulation bridge. In general, the elements of the articulation bridge are components of the telescope body. However, it is also possible to fasten the two barrel tubes rotatably to a bridge.
The two elements of the articulation bridge conventionally extend over a large part of the length of the barrel tubes. This can make grasping of a barrel tube more difficult when handling the telescope. It is also possible to provide two articulation joints which allow grasping around one of the barrel tubes. Care must be taken herein to ensure careful alignment of the articulation joints to one another.
When the telescope is put down, the articulation angle can become altered due to the pressure on the articulation bridge or the articulation joints, so that the pupil separation of the eyepieces must be brought to the individual eye separation again. An effective, robust fixing device for the adjusted pupil distance which can be actuated with the application of little force is difficult to achieve due to the unfavorable lever effect with a conventional bridge. In the case of an articulation bridge with two articulation points, a fixing device of this type cannot be achieved.
Due to the small articulation angle and the small joint diameter, it is also very difficult to apply a sufficiently accurate scale for the adjusted pupil separation at the joint sites. A prior adjustment to known individual eye separations is therefore not possible.
For packing the telescope, the barrel tubes are usually pulled far apart in order to enable accommodation in as flat a case as possible. When the barrel tubes are pressed together, the fingers of the user can become painfully trapped.
DE 106 130 C describes a prism binocular telescope comprising two prism binocular telescope housings with an essentially triangular cross-section. The optical axes of the objective lenses and of the eyepieces are parallel to one another in mutually opposed outer cross-sectional regions of the telescope housings. The telescope housings are inserted into a bridge along their full length. The bridge comprises a central column with a preferably triangular cross-section and support plates fastened thereon above and beneath, in which the telescope housings are mounted rotatable about the optical axes of the objective lenses. The eyepiece tubes are placed on the telescope housings outside the region of the support plates and are height-adjustable for focusing. On rotation of the telescope housings, the eyepiece tubes perform a partial rotation about the optical axes of the objectives, and this is useful for adjustment of the pupil separation. In the position of the smallest pupil separation, the column of the bridge lies in a form-fitting manner in the inner cross-sectional region formed by the telescope housings, so that in this position, a compact packing configuration results.
DE 100 54 138 A1 describes a binocular telescope wherein two objective lenses are firmly arranged on a base part. At the eyepiece-side portion of the base part, eyepiece tubes are mounted rotatable about the optical axes of the objective lenses, said eyepiece tubes also containing the prism system for image inversion. During pivoting of the eyepiece tubes for adjusting the pupil distance, similar difficulties occur as with telescopes which have an articulation bridge.
U.S. Pat. No. 5,973,830 A describes a binocular telescope with adjustment of the pupil separation. The two telescope barrels have parts which are designed distinctly offset relative to one another in the longitudinal direction for accommodating the objective lenses, the prism systems and the eyepieces. The prism systems create a very large offset of the optical axes of the objectives and the eyepieces. The partial regions of the telescope barrels with the objectives are rotatably set into a rigid bridge and lie close to one another. A clamping plate which is placed on the eyepiece-side prism portion of the telescope barrels and is connected to the bridge secures the telescope barrels against falling out of the bridge and permits rotation of the telescope barrels about the optical axes of the objective lenses. For setting the pupil separation, the oval housing portions with the prism systems must be manually pivoted relative to one another. The operation thereof suffers the same disadvantages as binoculars with an articulation bridge.
It is therefore an object of the invention to improve operation when grasping one of the barrel tubes, to secure against unintentional displacement the individual setting of the pupil separation to an eye separation and to enable flattened-out accommodation of the telescope in a case without changing the eye separation setting.